Turning multidimensional array into one-dimensional array [duplicate]

Question

I've been banging my head on this one for a while now.

I have this multidimensional array:

Array
(
    [0] => Array
        (
            [0] => foo
            [1] => bar
            [2] => hello
        )

    [1] => Array
        (
            [0] => world
            [1] => love
        )

    [2] => Array
        (
            [0] => stack
            [1] => overflow
            [2] => yep
            [3] => man
        )

And I need to get this:

Array
(
    [0] => foo
    [1] => bar
    [2] => hello
    [3] => world
    [4] => love
    [5] => stack
    [6] => overflow
    [7] => yep
    [8] => man
)

Any ideas?

All other solutions I found solve multidimensional arrays with different keys. My arrays use simple numeric keys only.

Duplicate of How to Flatten a Multidimensional Array? and many others. — deceze
– deceze ♦, Commented Dec 23, 2011 at 1:27
[look @ my solution in this post][1] [1]: stackoverflow.com/questions/6940217/… — Dexy86
– Dexy86, Commented Oct 30, 2012 at 20:29

deceze · Accepted Answer · 2015-06-18 07:15:43Z

94

array_reduce($array, 'array_merge', array())

Example:

$a = array(array(1, 2, 3), array(4, 5, 6));
$result = array_reduce($a, 'array_merge', array());

Result:

array[1, 2, 3, 4, 5, 6];

edited Jun 18, 2015 at 7:15

answered Dec 23, 2011 at 1:26

deceze♦

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2 Comments

deceze Over a year ago

This is not necessarily the best way to do it, it may be somewhat cryptic for one; I just like the functional approach and writing one-liners for the exercise. ;o)

raugfer Over a year ago

Second argument could be just 'array_merge'.

Community · Accepted Answer · 2017-05-23 12:10:01Z

42

The PHP array_merge^Docs function can flatten your array:

$flat = call_user_func_array('array_merge', $array);

In case the original array has a higher depth than 2 levels, the SPL in PHP has a RecursiveArrayIterator you can use to flatten it:

$flat = iterator_to_array(new RecursiveIteratorIterator(new RecursiveArrayIterator($array)), 0);

See as well: How to Flatten a Multidimensional Array?.

edited May 23, 2017 at 12:10

CommunityBot

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answered Dec 23, 2011 at 1:41

hakre

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3 Comments

stamster Over a year ago

SPL RecursiveIteratorIterator class is the best possible solution when you have a mixed array (keys with both N dimension and keys as strings/ints/whatever not array).

Chirag Patel Over a year ago

It is return only array value not key. how can i get key & value both?

hakre Over a year ago

@ChiragPatel: Recursive iteration over (then multiple) array(s) often has key collisions. The recursive iteration however does provide keys as well, just set the second parameter $use_keys of iterator_to_array() to true, see php.net/iterator_to_array

Don't Panic · Accepted Answer · 2018-04-25 16:04:51Z

26

As of PHP 5.6 this can be done more simply with argument unpacking.

$flat = array_merge(...$array);

answered Apr 25, 2018 at 16:04

Don't Panic

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2 Comments

hakre Over a year ago

As of PHP 7.4 this will also will work if $array has a count of zero (for exactly this use).

Jules Colle Over a year ago

this is the most clear and simple solution today

Grexis · Accepted Answer · 2011-12-23 01:20:39Z

13

This is really all there is to it:

foreach($array as $subArray){
    foreach($subArray as $val){
        $newArray[] = $val;
    }
}

answered Dec 23, 2011 at 1:20

Grexis

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1 Comment

Abdul Rehman Over a year ago

its not linear or logN

n00b · Accepted Answer · 2014-08-15 18:15:40Z

3

foreach ($a as $v1) {
    foreach ($v1 as $v2) {
        echo "$v2\n";
    }
}

where $a is your array name. for details

answered Aug 15, 2014 at 18:15

n00b

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2 Comments

Bun Over a year ago

This does not answer the question completly, he wants to populate a new array with the values. (However I do think they found a solution since the 2 years that this has been posted)

n00b Over a year ago

i also think that they found the result but i just wanted to share my view. thanks for the comment, no hard feelings :)

Hamid Naghipour · Accepted Answer · 2016-06-06 10:55:12Z

3

As of PHP 5.3 the shortest solution seems to be array_walk_recursive() with the new closures syntax:

function flatten(array $array) {
    $return = array();
    array_walk_recursive($array, function($a) use (&$return) { $return[] = $a; });
    return $return;
}

answered Jun 6, 2016 at 10:55

Hamid Naghipour

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Comments

rray · Accepted Answer · 2016-07-14 23:50:16Z

1

In PHP5.6 there other way to solve this problem, combining the functions, array_shift() to remove the first elemente of the original array, array_pus() to add items an new array, the important thing is the of ... splapt/elipse operator it will unpack the return of array_shitf() like an argument.

<?php

$arr = [
        ['foo', 'bar', 'hello'],
        ['world', 'love'],
        ['stack', 'overflow', 'yep', 'man', 'wow']
    ];

$new = [];
while($item = array_shift($arr)){
    array_push($new, ...$item);
}

print_r($new);

Output:

Array
(
    [0] => foo
    [1] => bar
    [2] => hello
    [3] => world
    [4] => love
    [5] => stack
    [6] => overflow
    [7] => yep
    [8] => man
    [9] => wow
)

Example - ideone

answered Jul 14, 2016 at 23:50

rray

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1 Comment

stamster Over a year ago

Works only for single dimensional arrays. For mixed use, only working solution is $new = iterator_to_array(new \RecursiveIteratorIterator(new \RecursiveArrayIterator($myArray)), null);

piet.t · Accepted Answer · 2017-01-04 09:05:43Z

1

I had used this code to resolve same type of problem. so you can also try this.

function array_flatten($array) { 

 if (!is_array($array))  
{ 
  return FALSE;  
}  
  $result = array(); 
foreach ($array as $key => $value)
{
  if (is_array($value))  
  {
   $result = array_merge($result, array_flatten($value));
  } 
  else  {
  $result[$key] = $value;   
  }  
}   
return $result; 
}

edited Jan 4, 2017 at 9:05

piet.t

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answered Oct 5, 2016 at 13:30

Kunwar Kishor

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Comments

Hassaan · Accepted Answer · 2018-12-27 13:08:00Z

1

This will make

array_walk_recursive($array, function($a) use (&$return) { $return[] = $a; });

edited Dec 27, 2018 at 13:08

Hassaan

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answered Jul 16, 2018 at 9:34

Rutunj sheladiya

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Comments

Roman · Accepted Answer · 2014-08-14 21:58:01Z

$blocked_dates = array(
                    '2014' => Array
                        (
                            '8' => Array
                                (
                                    '3' => '1',
                                    '4' => '1',                                     
                                    '6' => '1',                                     
                                    '10' => '1',
                                    '15' => '1',
                                    '25' => '1'

                                )

                        ),
                    '2015' => Array
                        (
                            '9' => Array
                                (
                                    '3' => '1',
                                    '4' => '1',                                    
                                    '6' => '1',                                     
                                    '10' => '1',
                                    '15' => '1',
                                    '25' => '1'

                                )

                        )    

                );

RESUTL(ONE DIMENTIONAL ARRAY) :

$unavailable_dates = array();
foreach ($blocked_dates as $year=>$months) {

    foreach ($months as $month => $days) {

        foreach ($days as $day => $value) {

            array_push($unavailable_dates,"$year-$month-$day");
        }

    }
}



$unavailable_dates = json_encode($unavailable_dates);
print_r($unavailable_dates);

OUTPUT : ["2014-8-3","2014-8-4","2014-8-6","2014-8-10","2014-8-15","2014-8-25","2015-9-3","2015-9-4","2015-9-6","2015-9-10","2015-9-15","2015-9-25"]

Minwork · Accepted Answer · 2019-02-26 19:41:21Z

-1

The quickest solution would be to use this array library:

$flattened = Arr::flatten($yourArray);

which will produce exactly the array you want

answered Feb 26, 2019 at 19:41

Minwork

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